Purpose: To evaluate incidence, time trends, geographic distribution, clinicopathologic presentation features, and prognostic factors for survival and relapse in gastrointestinal (GI) non-Hodgkin's lymphomas (NHLs).
Patients and methods: Over a 9-year period (1983 to 1991), 2,446 new NHL cases were recorded in a Danish population-based NHL registry (Danish Lymphoma Study Group [LYFO]). Of these, 306 (12.5%) were GI NHL (175 gastric, 109 intestinal, and 22 both sites). LYFO registry data were used for incidence rate (IR) assessment, and time-trend and geographic distribution analysis. Relative risk (RR) values for survival and relapse were identified by multivariate analysis.
Results: The mean annual, age-standardized IRs for gastric and intestinal NHL were 0.71/10(5) and 0.48/10(5) per year, respectively. Age-specific IRs for both localizations showed an exponential increase as a function of age. Time-trend analysis for the period 1983 to 1991 showed stable IRs for both localizations. Intestinal NHL was more frequent in males (male-to-female ratio, 2.0 v 1.3), and had a higher occurrence of disseminated disease, constitutional symptoms, high-grade histology, and T-cell phenotype (10% v 2%). Gastric NHL had more low-grade cases (38% v 19%), and almost all were of the mucosa-associated lymphoid tissue (MALT) type. The cause-specific 5-year survival rate was 63% for gastric NHL and 49% for intestinal NHL. The Musshoff staging system was an excellent discriminator between truly localized (stage I and II1) and disseminated cases (stage II2 to IV), particularly for gastric NHL, for which no survival difference was found between surgically and conservatively stage localized cases.
Conclusion: (1) No increase in the incidence of GI NHL was found over a 9-year observation period; (2) nonrandom spatial distribution of new GI NHL cases was observed; (3) factors that significantly increased the risk of death in gastric cases were presence of B symptoms (RR = 3.3), clinical stage is more than II1 (RR = 3.0), age more than 72 years (RR = 2.4), and elevated serum lactate dehydrogenase (s-LDH) level (RR = 2.0); and factors that increased the risk of death in intestinal cases were presence of B symptoms (RR = 3.2), age more than 58 years (RR = 2.8), and clinical stage more than I (RR = 2.1); (4) factors that significantly increased the risk of relapse in gastric cases were male sex and no radiotherapy in primary treatment; and in intestinal cases were T-cell phenotype and no surgery in primary treatment; (5) surgical staging, as opposed to thorough noninvasive staging, did not improve staging accuracy and final outcome in localized gastric NHL.